Resuscitation device with onboard processor

ABSTRACT

A resuscitator has a patient airway interface device, a bag, a flow passage coupled between the bag and patient airway interface device, and a sensor assembly. The patient airway interface device may be a mask or an endotracheal tube. The sensor assembly has a display, at least one sensor coupled to the flow passage and configured to provide a measurement of at least one parameter, and a processor coupled to the display and the at least one sensor. The processor is configured to receive the measurement from the sensor and provide information on the display based on the received measurement. The information may include a current breath rate, a pressure-vs-time curve, and guidance to the user to assist in achieving a target breath rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 13/829,281 entitled “RESUSCITATION DEVICE WITHONBOARD PROCESSOR,” filed on Mar. 14, 2013, which is hereby incorporatedby reference in its entirety for all purposes.

BACKGROUND

Field

The present disclosure generally relates to manual resuscitation devicesand, in particular, a resuscitator that incorporates electronic sensingand processing.

Description of the Related Art

A resuscitator, sometimes referred to as a bag valve mask (BVM) or bythe proprietary name “Ambu bag,” is a hand-held device used to providepositive pressure ventilation to a patient who is not breathing or whois breathing inadequately. The resuscitator is a normal part of a “crashcart” used within a hospital or a resuscitation kit provided toambulance crew. A resuscitator may also be used in an operating room toventilate an anaesthetized patient prior to attachment of a mechanicalventilator. A resuscitator may be self-filling with air or provided witha source of breathing gas, such as oxygen, to increase the oxygenationof the patient.

FIG. 1 depicts a conventional resuscitator 10 that is connected to aline 20 that provides oxygen or other breathing gas. A bag 14 isconnected to a mask 12 by a flow channel 16 that also has a valveassembly 18 that prevents backflow into the bag 14 and diverts exhaledgas to the atmosphere. An accumulator bag 22 is connected at thejunction of the bag 14 and line 20 to accumulate a reservoir of oxygensuch that the self-expansion of the bag 14 is not limited by the flowrate of line 20.

When using a resuscitator, there is a risk of over-inflating the lungs.This can lead to pressure damage to the lungs themselves and can alsocause air to enter the stomach, causing gastric distension which canmake it more difficult to inflate the lungs. Over-inflation may alsocause the patient to vomit, which can cause additional airway problemsbeyond the original breathing difficulty.

FIG. 2 depicts another conventional resuscitator 30 having a mechanicalpressure gauge 32 connected to the flow channel 16. The gauge 32 ismarked with a green zone to indicate the desirable range of inflationpressure as well as yellow and red zones to indicate zones of excessinflation pressures. These types of mechanical gauges have limitedresolution and reading such a gauge can be a challenge for caregivers asthe gauge provides only an instantaneous reading and the caregivercannot pay constant attention to the gauge as they may be performingother actions, for example striving to maintain a proper seal of themask to the patient's face and monitoring other symptoms and aspects ofthe patient's condition.

SUMMARY

The resuscitator disclosed herein provides automatic monitoring ofvarious aspects of the operation of the resuscitator as well as thepatient's breathing and exhaled breath. The information gathered by theresuscitator can be provided in real-time to the caregiver to aid intheir resuscitation efforts or stored for later review and analysis.

In certain embodiments, a resuscitator is disclosed that includes apatient airway interface device, a bag, a flow passage coupled betweenthe bag and patient airway interface device, and a sensor assembly. Thesensor assembly may have a display, at least one sensor coupled to theflow passage and configured to provide a measurement of at least oneparameter, and a processor coupled to the display and the at least onesensor. The processor may be configured to receive the measurement fromthe at least one sensor and provide information on the display based onthe received measurement.

In certain embodiments, a resuscitator is disclosed that includes apatient airway interface device, a bag, a flow passage coupled betweenthe bag and patient airway interface device, and a sensor assemblyhaving an indicator, at least one sensor coupled to the flow passage andconfigured to provide a measurement of at least one parameter, and aprocessor coupled to the indicator and the at least one sensor. Theprocessor is configured to receive the measurement from the at least onesensor and actuate the indicator based on the received measurement.

In certain embodiments, a method is disclosed that includes the steps ofmeasuring at least one of a flow rate, a pressure, a temperature, a pH,and a chemical marker in the exhaled breath of a patient; and actuatingan indicator so as to provide information related to at least one of abreath rate, a tidal volume, a pressure-vs-time curve, a presence of achemical in the patient's breath, or a condition of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding and are incorporated in and constitute a part of thisspecification, illustrate disclosed embodiments and together with thedescription serve to explain the principles of the disclosedembodiments. In the drawings:

FIG. 1 depicts a conventional resuscitator.

FIG. 2 depicts a conventional resuscitator having a mechanical pressuregauge.

FIG. 3 is a schematic representation of an exemplary resuscitatoraccording to certain aspects of the present disclosure.

FIG. 4 is a block diagram of the example sensor module that is part ofthe resuscitator of FIG. 3 according to certain aspects of the presentdisclosure.

FIG. 5 is a block diagram of the example processor that is part of thesensor module of FIG. 4 according to certain aspects of the presentdisclosure.

FIGS. 6A-6B are cross-sections of an exemplary flow sensor according tocertain aspects of the present disclosure.

FIG. 6C depicts another embodiment of the flow sensor according tocertain aspects of the present disclosure.

FIG. 7A is an exploded view of an exemplary pressure sensor 280according to certain aspects of the present disclosure.

FIGS. 7B-7C are cross-sections of the assembled pressure sensor 280 ofFIG. 7A according to certain aspects of the present disclosure.

FIG. 8 is an exemplary display of information provided by the processoraccording to certain aspects of the present disclosure.

DETAILED DESCRIPTION

The resuscitator disclosed herein provides automatic monitoring ofvarious aspects of the operation of the resuscitator as well as thepatient's breathing and exhaled breath. The information gathered by theresuscitator can be provided in real-time to the caregiver to aid intheir resuscitation efforts or stored for later review and analysis.

In general, the disclosed resuscitator may include sensors thatcontinuously or intermittently measure the pressure within the patientairway interface device and, during an exhalation by the patient, maymeasure one or more of chemical markers or particular chemicals,temperature, or pH. The resuscitator may also provide guidance to thecaregiver such as a metronome of the optimal rate of inhalations, visualor audible alarms, and verbal communication.

This disclosure describes embodiments that include a mask intended to beplaced over a patient's nose and/or mouth so as to form a sealedconnection to the patient's airway. It should be understood that othertypes of patient airway interfaces may be used in place of the mask, forexample an endotracheal tube, without departing from the scope of thisdisclosure. In general, the term “mask” includes all types of patientairway interface devices.

In the following detailed description, numerous specific details are setforth to provide a full understanding of the present disclosure. It willbe apparent, however, to one ordinarily skilled in the art thatembodiments of the present disclosure may be practiced without some ofthe specific details. In other instances, well-known structures andtechniques have not been shown in detail so as not to obscure thedisclosure. In the referenced drawings, like numbered elements are thesame or essentially similar. Reference numbers may have letter suffixesappended to indicate separate instances of a common element while beingreferred to generically by the same number without a suffix letter.

FIG. 1 depicts a conventional resuscitator 10. A flexible mask 12 isconfigured to be placed over a patient's mouth and nose. The bag 14 isconnected to the mask 12 by a flow channel 16. A valve assembly 18 isattached to the flow channel 16 and includes a valve (not visible inFIG. 1) that prevents an exhaled breath from entering the bag 14 anddiverts the exhaled breath out a port to the ambient atmosphere. Thisresuscitator 10 may be attached to a line 20 that provides oxygen, orother breathing gas, with an accumulator bag 22 connected at thejunction of the bag 14 and line 20 to accumulate a reservoir of oxygensuch that the self-expansion of the bag 14 is not limited by the flowrate of line 20.

FIG. 2 depicts another conventional resuscitator 30 having a mechanicalpressure gauge 32 connected to the flow channel 16. The gauge 32 ismarked with a green zone 32A to indicate the desirable range ofinflation pressure as well as a yellow zone 32B and a red zone 32C toindicate zones of excess inflation pressures. As the gauge 32 providesonly an instantaneous reading, there is no information regarding thehistory of the pressure being provided during the inhalation intervalsor an average pressure. In addition, the mechanical inertia of the gauge32 may delay or dampen the displayed value compared to the trueinstantaneous pressure in the flow channel 16.

FIG. 3 is a schematic representation of an exemplary resuscitator 100according to certain aspects of the present disclosure. The resuscitator100 includes a bag 110 connected to a mask 112 through a flow passage114. In certain embodiments, the bag 110 is manually squeezed to forceair or other breathing gas into the patient's lungs, after which the bag110 self-expands to draw in new air or gas. A valve assembly 116,containing a shutter valve (not visible in FIG. 3) or equivalent, isattached to the flow passage 114 to divert exhaled gas to theatmosphere. A sensor module 120 that includes a display 132 is coupled,in this example, to the flow passage 114 between the mask 112 and thevalve assembly 116. In certain embodiments, the sensor assembly 120 isoperatively coupled to the valve assembly 116. The sensor assembly 120is discussed in greater detail with respect to FIG. 4. In certainembodiments, the mask 112 may be replaced by other types of breathinginterface devices, for example an endotracheal tube or laryngeal maskairway (not shown in FIG. 3). In certain embodiments, the bag 110 drawsin a breathing gas, for example oxygen, through an attached line 118. Incertain embodiments, a reservoir (not shown in FIG. 3) may be attachedproximate to the junction of the line 118 and bag 110 to provide a largevolume of the breathing gas such that the self-expansion of the bag 110is not limited by the flow rate of line 118.

FIG. 4 is a block diagram of the example sensor module 120 that is partof the resuscitator 100 of FIG. 3 according to certain aspects of thepresent disclosure. The sensor module 120 may include one or more of aprocessor 122, a timer 124, a pressure sensor 126, a chemical sensor128, a communication (comm) module 130, a display 132, an alarm 134, atemperature sensor 136, and a pH sensor 138 that are interconnected by anetwork 142. Other elements common to electronic equipment, for examplebatteries or power supplies, touch screen interfaces, buttons, switches,and connectors, that are known to those of skill in the art are omittedso as not to obscure the disclosed features. The processor 122 isdiscussed in greater detail with respect to FIG. 5. The flow sensor 200is discussed in greater detail with respect to FIG. 6.

The pressure sensor 126 may be any device or mechanism configured tomeasure a gas pressure as are known to those of skill in the art. Thepressure sensor 126, as well as one or more of the other sensors 128,136, 138, and 200, may include resistive, capacitive, piezoelectric, orsolid state electronic devices with or without embeddedsignal-conditioning circuitry. In certain embodiments, the pressuresensor 126, or other sensor, may be configured to detect an initialmanual compression of the resuscitator bag 110 and trigger certainfunctions, for example turning on the display 132 and powering up otherelements of the sensor module 120. In certain embodiments, the pressuresensor 126 or other sensor may be configured to detect inactivity over adetermined period of time and trigger other functions, for exampleturning off the display 132 and placing the CPU in a low-power state toconserve power.

The chemical sensor 128 may include one or more sensors that may beconfigured to detect in the patient's exhaled breath the presence oramount of certain chemical markers associated with certain physicalattributes. In certain embodiments, the chemical sensor 128 may detector measure markers associated with a level of alcohol or a drug in thepatient's blood. In certain embodiments, the chemical sensor 128 maydetect or measure a peroxide level in the patient's breath that may beassociated with asthma. In certain embodiments, the chemical sensor 128may measure one or more partial pressures of certain gases, for examplecarbon dioxide, in the patient's exhaled breath.

The comm module 130 may include a wireless communication system, forexample using Bluetooth® (IEEE 802.15.1) or Wi-Fi (IEEE 802.11) elementsand protocols, that allows the sensor module 120 to communicate withexternal equipment. In certain embodiments, the comm module 130 mayinclude a port for connection of a communication cable, for example aCATS cable, to enable communication with external equipment. In certainembodiments, the comm module 130 may include a port for a removablemedia, for example a USB port to connect to a “thumb drive,” or a driveconfigured to read and/or write to a removable media, for example a CDor DVD.

The display 132 may be any audio or visual device as known to those ofskill in the art. In certain embodiments, the display 132 may include acolor or monochrome two-dimensional visual display that may include oneor more of light emitting diodes (LEDs), liquid crystals, “electronicpaper” such as electrophoretic display technologies, orelectroluminescent elements. In certain embodiments, the display 132 maybe an audio device (132 b in FIG. 3) such as a speaker, buzzer, or tonegenerator. In certain embodiments, the display 132 may be a visualindicator (132 a in FIG. 3) such as a single monochrome LED, a group ofLEDs of various colors, an incandescent bulb, or a linear array ofsingle light-emitting elements.

The alarm 134 may include visual indicators, for example lights that maybe selectably illuminated, or audible indicators, for example a speaker,a tone generator, or a buzzer. In certain embodiments, the alarm 134 maybe a visual element provided on the display 132. In certain embodiments,a visual or audible signal may be provided continuously or duringnon-alarm conditions. For example, a tone of a first frequency orcombination of frequencies may be provided when the caregiver isoperating the resuscitator within the desired range of pressure. Incertain embodiments, the visual or audible signal may change, forexample to a tone of a second frequency or combination of frequencies,when the pressure exceeds the desired range.

In certain embodiments, the resuscitator 100 may have a disposableportion, for example the bag 110, flow passage 114, and mask 112, towhich a re-useable portion, for example the sensor module 120, isattached. In certain embodiments, the disposable portion may include asensor, for example a flow sensor such as shown in FIG. 6, thatfunctionally connects to the processor 122. In certain embodiments, theentire resuscitator 100 may be disposable.

FIG. 5 is a block diagram of the example processor 122 that is part ofthe sensor module 120 of FIG. 4 according to certain aspects of thepresent disclosure. The processor 122 may include one or more of acentral processor unit (CPU) 150, a display driver 152, ananalog-to-digital converter (ADC) 154, an alarm driver 156, a commmodule 158, a memory 160, a timer 162, a clock 164, and a peripheralcontrol interface 166 that are interconnected by an internal network168. Various components may be connected directly to other modules ofthe sensor module 122, for example the display driver 152 may beconnected directly to the display 132. In certain embodiments, variouscomponents may be connected to other modules of the sensor module 122through the internal network 168, comm module 158, and an externalnetwork.

The memory 160 may include transitory computer-readable media such asrandom access memory (RAM) as well as non-transitory computer-readablemedia that may include magnetically encodable media such as hard disks,solid-state memory (SSD), flash memory data storage devices such asthumb drives, and read-only memory (ROM). The memory 160 may beconfigured to store operational instructions that may be retrieved bythe CPU 150 to configure the CPU 150 so as to be able to perform variousfunctions. The memory 160 may also contain a look-up table comprisinglimits or other information that may be used to interpret themeasurements of the various sensors, alone or in combination. In certainembodiments, the memory may store instructions and information relatedto the operation and testing of the resuscitator, for example batterylife, self-test procedures, errors code, etc. In certain embodiments,the memory 160 may store calibration instructions and information foruse in calibrating elements of the resuscitator 100.

The peripheral controls interface 166 may be coupled to external deviceswithin the sensor module 120, for example a touchscreen, buttons, andswitches, to allow a user to interact with the CPU 150 so as to initiatedesired functions. In certain embodiments, the peripheral controlsinterface 166 may be operatively coupled to the valve assembly 116 soas, for example, to control a restrictor (not shown in FIG. 3) thatmaintains a desired minimum pressure within the mask 112.

In certain embodiments, the CPU 150 may be configured to receivemeasurements made by the pressure sensor 126 through the ADC 154. Incertain embodiments, the CPU 150 may store a portion of thesemeasurements in the memory 160. In certain embodiments, the CPU 150 maydisplay a portion of the measurements on the display, for example as ameasurement-vs.-time curve that may be overlaid with zones of pressureindicating desirable and/or undesirable ranges of pressure. In certainembodiments, the CPU 150 may receive measurements from one or morechemical sensors 128 and analyze the measurements. In certainembodiments, the CPU 150 may provide indications to the caregiver ofcertain physical conditions associated with the measurements of thechemical sensors 128, for example a warning that the patient has acertain level of an anesthetizing agent in their blood. In certainembodiments, the CPU 150 may provide other information or warnings tothe caregiver related to the measured chemical markers in the exhaledbreath as known to those of skill in the art.

In certain embodiments, the CPU 150 may provide real-time guidance to acaregiver using the resuscitator 100 by providing a visual or audiblemetronome signal through the display 132 or alarm 134 at a target rateof inhalation intervals or cycles. In certain embodiments, the CPU 150may adjust the metronome signal to an upper or lower value, within anacceptable range of rates of inhalation intervals, based on the rate ofinhalation intervals as measured by the pressure sensor 126.

In certain embodiments, the CPU 150 may provide real-time guidance to acaregiver using spoken phrases, for example “current rate is 20 breathsper minute, please slow to 12 breaths per minute,” through a display 132that comprises a speaker. In certain embodiments, the CPU 150 mayprovide real-time guidance to a caregiver through a display 132 thatcomprises a flashing, variably colored light, for example a lightflashing at a target inhalation interval with a color that indicateswhether the resuscitator is currently being actuated at a rate that ishigher than, within, or less than an acceptable range. In certainembodiments, the current rate being displayed may be a time-average of apast number, for example three, inhalation intervals.

In certain embodiments, the CPU 150 may combine measurements frommultiple sensors to calculate other parameters related to the patient'scondition or the resuscitation actions, for example a tidal volume orexhalation pressure.

In certain embodiments, the CPU 150 may store an entire history of aresuscitation event, for example including one or more of pressures,partial pressures, and measured chemical markers, and download thishistory through the comm modules 158 and 130 to an external system, forexample a personal computer (PC). This history may enable a review ofthe resuscitation event and the actions of the caregiver during theevent. In the case where a patient does not survive, this history mayprovide evidence of factors, such as asthma, that may have contributedto the patient's death. If the resuscitator 100 were used with a manikinor other training aid, this history may provide the ability toquantitatively evaluate the performance of the user.

In certain embodiments, the CPU 150 may be configured to accept newprogramming instructions, for example built-in operating system (BIOS)programming and settings, firmware, or software, or new information ,for example a look-up table of limits and parameters, and store theseinstructions and information in memory 160.

FIGS. 6A-6B are cross-sections of an exemplary flow sensor 200 accordingto certain aspects of the present disclosure. The flow sensor 200includes a rigid porous plate 202 having a plurality of contacts 206distributed over the plate 202. A flexible disk 204 is attached, incertain embodiments, to the middle of plate 202. FIG. 6A depicts theconfiguration of the sensor 200 in the absence of a flow of gas past thesensor. All, or at least a majority, of the contacts 206 are in contactwith or otherwise actuated by the flexible disk 204 so as to provide anindication that the disk is in a first configuration, for example flatagainst the plate 202.

FIG. 6B depicts the sensor 200 while a gas flows past the sensor 200, asindicated by the flow path 250. The flexible disk 204 deflects asindicated by the arrows 260 to a second configuration wherein onlysensors 206B are in contact with disk 204 while sensors 206A are not incontact with the disk 204. The number of contacts 206A vs. 206B providesan indication of the amount of deflection of disk 204 and therefore anindication of the rate of flow of the gas passing the sensor 200.

If a sensor 200 is placed in the flow passage 114 between the mask 112and the valve assembly 116, or in the exhalation port outside of thevalve assembly 116, it may be possible to measure the exhalation flowrate. In certain embodiments, the CPU 150 may combine the measurementfrom pressure sensor 126 and the measurement from flow sensor 200 tocalculate a tidal volume.

FIG. 6C depicts another embodiment 201 of the flow sensor according tocertain aspects of the present disclosure. The flow sensor 201 hascontacts 207 that are placed on the surface of a curved structure 203that is disposed downstream of the flexible disk 205, with respect tothe direction of measurement. The disk 205 bends away from theundeformed position, shown in dashed line, as indicated by the arrows261 in response to the flow 251. As the disk 205 increasingly bends, itcomes into contact with an increasing number of the contacts 207. Bycomparing the number and position of contacts 207B that are in contactwith the disk 205 to the number and location of the contacts 207A thatare not in contact with the disk 205, the configuration of the disk 205can be determined.

FIG. 7A is an exploded view of an exemplary pressure sensor 280according to certain aspects of the present disclosure. The sensor 280includes a flexible disk 282 and a wall 284 that, in this embodiment, iscircular. In this embodiment, the wall 84 is formed on a substrate 296with a series of conductive rings 286 formed on the substrate 296 withinthe wall 284. The disk 282 has, in this embodiment, a series of radialconductive strips 290, 292 formed on the underside (the disk 282 isshown as transparent in FIG. 7A to make the strips 290, 292 visible). Incertain embodiments, the strips 292 are of variable length and arrangedsuch that more strips 292 contact the rings 286 as the disk 282 isincreasingly deformed.

FIGS. 7B-7C are cross-sections of the assembled pressure sensor 280 ofFIG. 7A according to certain aspects of the present disclosure. Thisdisk 282 is sealingly attached to the wall 284 so as to form an interiorvolume 294 over the substrate 296. FIG. 7B shows the pressure sensor 280in an initial configuration wherein the pressures within interior volume294 and external volume 298 are equal. In certain embodiments, theexternal volume 298 may be the interior of flow passage 114 of FIG. 3.In certain embodiments, the interior volume 294 may be vented to theambient atmosphere, for example external to the flow passage 114, suchthat pressure measured by the pressure sensor 280 is gauge pressure. Asthe pressure in the external volume 298 increases, the disk 282 willdeform as shown in FIG. 7C and one or more of the radial strips 290, 292(not visible in FIGS. 7B-7C) on disk 282 will contact one or more of theconcentric rings 286. By determining which rings 286 are interconnectedby contact with the strips 290, 292, for example by measuring theresistance between pairs of rings 286, using a resistance measurementdevice (not shown in FIGS. 7A-7C), the deformed shape of the disk 282can be determined and therefore the pressure in the external volume 298can be determined. With the appropriate arrangement of the radial strips292, the change in resistance may be non-linear with increaseddeformation, thereby at least partially compensating for any non-lineardeformation of the disk 282 in response to an incremental change in thepressure in external volume 298. In the example wherein the externalvolume 298 is the interior of flow passage 114, the pressure in theexternal volume 298 typically fluctuates between ambient pressure and ahigher pressure, thus deflecting the disk 282 against the concentricrings 286 to a greater or lesser degree.

It will be apparent that the disposition of the concentric rings 286 andradial conductive strips 290, 292 may be interchanged such that theconcentric conductive rings are formed on the underside of the disk 282while radial conductive lines of varying length are provided on thesurface of substrate 296 within the wall 284 without departing from thescope of this disclosure. Methods of selectably measuring the resistancebetween pairs of the rings 286, in the embodiment shown in FIGS. 7A-7C,or of radial conductive lines formed on the substrate, in an alternateembodiment, are known to those of skill in the art and are not shownherein.

FIG. 8 is an exemplary display 300 of information provided by theprocessor 122 according to certain aspects of the present disclosure.The display 300 depicts examples of four sections 310, 320, 330, and 340each displaying one or more examples of information. In certainembodiments, the display 300 may provide more or fewer elements ofinformation.

Section 310 displays an exemplary pressure-vs.-time curve 213, with thecurrent time at the right. The plot is overlaid with a target peakinhalation pressure line 314 and a excess-pressure area 316.

Section 320 displays the breath rate, i.e. the rate of inhalationintervals. The display 320 includes a marker 324 indicating the currenttime-averaged breath rate within a range bar 322 with minimum andmaximum rates indicated with labels and shaded areas 326. The value isshown as a numerical value 325 that, in certain embodiments, may includea notation, for example a notation that the value is a 10-secondaverage.

Section 330 displays visual indicators 332 associated with variousphysical attributes. The box 334 displays the calculated blood-alcoholcontent based on the measured marker in the patient's breath. The box336 would identify a drug, if detected.

Section 340 displays the elapsed time since the initiation of aresuscitation event. The box 342 displays the value and box 344 displaysthe units of time, which may initially be “seconds” and later change to“minutes” after a certain time interval has elapsed.

It can be seen that the disclosed embodiments of a resuscitation deviceshaving an onboard processor provides improved access to accuratemeasurements of variables related to both the functioning of theresuscitation device as well as the physiological functioning of thepatient. These variables may be easily read by the caregiver during theprocedure and/or stored for later analysis or training purposes.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. While theforegoing has described what are considered to be the best mode and/orother examples, it is understood that various modifications to theseaspects will be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to other aspects. Thus,the claims are not intended to be limited to the aspects shown herein,but is to be accorded the full scope consistent with the languageclaims, wherein reference to an element in the singular is not intendedto mean “one and only one” unless specifically so stated, but rather“one or more.” Unless specifically stated otherwise, the terms “a set”and “some” refer to one or more. Pronouns in the masculine (e.g., his)include the feminine and neuter gender (e.g., her and its) and viceversa. Headings and subheadings, if any, are used for convenience onlyand do not limit the invention.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as an “embodiment” does not imply that suchembodiment is essential to the subject technology or that suchembodiment applies to all configurations of the subject technology. Adisclosure relating to an embodiment may apply to all embodiments, orone or more embodiments. A phrase such an embodiment may refer to one ormore embodiments and vice versa.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs.

The terms “include,” “have,” and the like are intended to be inclusivein a manner similar to the term “comprise” as “comprise” is interpretedwhen employed as a transitional word in a claim.

No claim element is to be construed under the provisions of 35 U.S.C.§112, sixth paragraph, unless the element is expressly recited using thephrase “means for” or, in the case of a method claim, the element isrecited using the phrase “step for.”

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims.

What is claimed is:
 1. A pressure sensor comprising: a substrate; a wallformed on the substrate; one of a plurality of concentric conductiverings and a plurality of radial conductive strips is formed on thesubstrate within the wall; a flexible disk coupled to the wall so as toform an inner volume; the other of the plurality of concentricconductive rings and the plurality of radial conductive strips is formedon the disk; and wherein deformation of the flexible disk due to apressure differential between a first pressure within the inner volumeand a second pressure outside of the inner volume will cause at leastone of the radial conductive strips to contact at least one of theconcentric conductive rings.
 2. The sensor of claim 1, wherein theplurality of concentric conductive rings and the plurality of radialconductive strips are formed on inner surfaces of the substrate and theflexible disk.
 3. The sensor of claim 1, wherein the number ofconcentric conductive rings contacted by the at least one radialconductive strip is related to a magnitude of the pressure differential.4. A pressure sensor comprising: a substrate spaced apart from aflexible disk, and an inner volume formed therebetween; one of aplurality of concentric conductive rings and a plurality of radialconductive strips formed on a surface of the substrate; the other of theplurality of concentric conductive rings and the plurality of radialconductive strips formed on a surface of the disk; and whereindeformation of the flexible disk due to a pressure differential betweena first pressure within the inner volume and a second pressure outsideof the inner volume will cause at least one of the radial conductivestrips to contact at least one of the concentric conductive rings. 5.The sensor of claim 4, wherein a wall extends from the substrate to theflexible disk.
 6. The sensor of claim 4, wherein the plurality ofconcentric conductive rings and the plurality of radial conductivestrips are formed on inner surfaces of the substrate and the flexibledisk.
 7. The sensor of claim 4, wherein the number of concentricconductive rings contacted by the at least one radial conductive stripis related to a magnitude of the pressure differential.
 8. The sensor ofclaim 4, wherein the inner volume is vented to an ambient atmosphere. 9.A resuscitator comprising: a patient airway interface device, a bag, anda flow passage coupled between the bag and patient airway interfacedevice; a sensor assembly comprising a display and a pressure sensorcoupled to the flow passage and configured to provide a measurement ofat least one pressure, the pressure sensor comprising: a substratespaced apart from a flexible disk, and an inner volume formedtherebetween; one of a plurality of concentric conductive rings and aplurality of radial conductive strips formed on a surface of thesubstrate; the other of the plurality of concentric conductive rings andthe plurality of radial conductive strips formed on a surface of thedisk; wherein deformation of the flexible disk due to a pressuredifferential between a first pressure within the inner volume and asecond pressure outside of the inner volume will cause at least one ofthe radial conductive strips to contact at least one of the concentricconductive rings; and a processor coupled to the display and thepressure sensor, the processor configured to receive the measurementfrom the pressure sensor and provide information on the display based onthe received measurement.
 10. The resuscitator of claim 9, wherein theinformation provided on the display further comprises pressureinformation.
 11. The resuscitator of claim 10, wherein the informationcomprises a pressure-vs-time curve.
 12. The resuscitator of claim 9,wherein the information further comprises an alarm.
 13. The resuscitatorof claim 9, wherein the information further comprises real-time guidancerelated to operation of the resuscitator.
 14. The resuscitator of claim9, wherein: the sensor assembly comprises a memory coupled to theprocessor; and the processor is configured to store a portion of themeasurement in the memory.
 15. The resuscitator of claim 9, wherein thepatient airway interface device comprises a mask.
 16. The resuscitatorof claim 9, wherein the patient airway interface device comprises anendotracheal tube.
 17. A method comprising the steps of: measuring apressure in exhaled breath of a patient using at least one pressuresensor comprising: a substrate spaced apart from a flexible disk, and aninner volume formed therebetween; one of a plurality of concentricconductive rings and a plurality of radial conductive strips formed on asurface of the substrate; the other of the plurality of concentricconductive rings and the plurality of radial conductive strips formed ona surface of the disk; wherein deformation of the flexible disk due to apressure differential between a first pressure within the inner volumeand a second pressure outside of the inner volume will cause at leastone of the radial conductive strips to contact at least one of theconcentric conductive rings; and actuating an indicator so as to provideinformation related to the pressure measurement including at least oneof a breath rate, a tidal volume, a pressure-vs-time curve, or acondition of the patient.
 18. The method of claim 17, further comprisingthe step of actuating an indicator so as to provide guidance related toachieving at least one of a target breath rate and a target tidalvolume.
 19. The method of claim 17, further comprising venting the innervolume to an ambient atmosphere.
 20. The method of claim 17, whereinmeasuring a pressure comprises measuring a resistance between two ormore rings connected by a strip.